1. Field of the Invention
This invention relates to die presses, as used to stamp workpieces, and, more particularly, to a die press with a workpiece holder that is automatically controlled as the die press is operated.
2. Background Art
Hydraulically operated die presses are commonly used to stamp out tubular stock so as to facilitate formation of furniture and the like therefrom. These presses are conventionally operated using a reciprocatively mounted die holder which forcibly moves a cutting die thereon against a workpiece held strategically positioned on a bed relative to which the die holder moves.
It is important with such presses that workpieces be held positively in place. The workpieces are subjected to very large forces during press operations. Inadvertent release of the workpiece as a press operation is performed may cause destruction of the workpiece, damage to the press and/or injury to the press operator.
It is conventional to use a hydraulically or pneumatically operated cylinder to urge a slidable workpiece holder against a workpiece to maintain the same in place. While such cylinders generally effectively hold workpieces in place, they have numerous drawbacks.
The hydraulic cylinder takes up a significant amount of valuable space. The result is a relatively large overall press size. Further, the cylinder interferes with the press operator's access to the workpiece. Often this results in improper location of the workpiece by the operator on the press so that the workpiece is improperly formed. Accuracy and consistency in processing are thus difficult to achieve.
A further drawback with the conventional workpiece holders utilizing hydraulic/pneumatic cylinders is that the press operator must separately control the cylinder during an operation. The extra control step is inconvenient and time consuming. For example, the press operator must align the workpiece where desired and then manually operate the cylinder to lock the workpiece in place. After the press operation is completed, the press operator retracts the cutting die and then manually releases the pressure on the cylinder so that the workpiece can be removed from the press.